1. Field of the Invention
This invention relates generally to a method of adhesively bonding a resin portion of a denture base to a metallic portion thereof or of adhesively bonding a dentine to a restorative dental material such as an inlay, a crown or the like by using either adhesive resin or dental cement such as glassionomer cement, polycarboxylate cement or the like. More particularly, the invention relates to a method of improving the quality of the surface of an adherend metallic portion so as to impart stable and high adhesive strength to adhesively bonded portions formed by any of the above-described adhesion methods as well as good water resistance to the adherend surfaces of the adhesively bonded portions.
2. Description of the Related Art
In the field of dental treatment, various kinds of adhesives have recently been developed, such as dental cements or adhesive resins of the type which can be used in contact not only with dentine but with metallic portions.
The adhesives of these conventional types commonly exhibit, after adhesion, extremely superior adhesiveness with respect to Co-Cr alloys and Ni-Cr alloys in a dry atmosphere, but the adhesiveness deteriorates to a material extent in an environment in which water is present. In addition, with respect to rare metals, the aforesaid conventional adhesives are not able to yield satisfactory adhesiveness even in a dry atmosphere since the activity of rare metal surfaces is intrinsically low with respect to the above-described cement and adhesive resin.
In order to overcome the disadvantages described above, various metal surface treatments such as sandblasting treatment, 400.degree. C. high-temperature oxidation treatment, acid treatment, treatment utilizing electrodeposition with tin, and treatment utilizing coating with a glass layer (SiOx-C) have been developed, and attempts have been made to reduce them to practice.
However, even if a treatment is employed which comprises, singly or in combination, the aforesaid treatments such as sandblasting treatment, 400.degree. C. high-temperature oxidation treatment and acid treatment, it is impossible to obtain satisfactory adhesive strength and, further, adherend surfaces may naturally peel due to being immersed in water.
As compared with the aforesaid treatments such as sandblasting treatment, 400.degree. C. high-temperature oxidation treatment and acid treatment, a treatment utilizing electrodeposition with tin or coating with a glass layer can bring about superior adhesiveness and better water resistance of the adherend surfaces. However, systems utilizing electrodeposition with tin, which typically comprise an electrodeposition apparatus, an electrodeposition liquid, a masking set and a cleaning liquid, present a number of problems. First, a tin-electrodeposition system of this kind is expensive; second, the operation is complicated; and, third, the electrodeposition liquid (e.g., Sn-100) readily deteriorates due to oxidation.
On the other hand, a treatment based on the coating of a glass layer requires an apparatus for depositing SiOx-C on the surface of an alloy and also entails the use of chemical agents such as organic silane, a silane coupling agent, and so on. In addition, this method not only necessitates a very expensive apparatus as in the case of a treatment utilizing electrodeposition with tin, but the period during which such chemical agents can be stored is short and a complicated operation is required.